1. Field of the Invention
The invention relates to a battery monitoring device.
2. Description of Related Art
There is a conventional semiconductor circuit in which when a diagnosis is performed on the equalization function of an equalization switching element in a discharge circuit, an initializing operation is performed such that a capacitor in a comparison circuit is charged with electric power corresponding to a difference between a voltage of a signal line and a threshold voltage, and another capacitor in the comparison circuit is charged with electric power corresponding to a difference between a voltage of another signal line and the threshold voltage. In a comparison operation, signal lines are connected to each other such that a voltage is input to each of the capacitors. In the case where the equalization process is not performed, when the output is at the L level (LOW level), it is determined that the equalization function is normally performed, and when the output is at the H level (HIGH level), it is determined that there is a failure, and in the case where the equalization process is performed, when the output is at the H level, it is determined that the equalization function is normally performed, and when the output is at the L level, it is determined that there is a failure (for example, refer to Japanese Patent Application Publication No. 2012-147587).
In the above-described circuit in related art, when there is a leak in the capacitor, the detected voltage of the capacitor is smaller than the actual voltage of the capacitor, and therefore, over-charging may occur. Further, over-charging may be caused when there is a leak in an electric element connected in parallel to a battery cell whose voltage is monitored, as well as when there is a leak in the electric element such as the capacitor.